Biped locomotion robot

ABSTRACT

The movement analysis becomes easy and the control of all the movement systems is realized better through the initialization of the multiple coordinate systems. The fundamental body portion  6  is coupled to a foot portion  5  through a first joint portion  7 , a first link  3 , a second joint portion  8 , a second link  4 , and a third joint portion  9 . The rigidity of the first link  3  is lower than that of the fundamental body portion  6 , and the rigidity of the second link  4  is lower than that of the second link  4 . It is possible to position the second link  4  and the foot portion  5  in a high precision to a mechanical origin which is predetermined to the fundamental body portion, for the reason of the rigidity relation. Handle portions  13  are coupled in two positions to the fundamental body portion  6 . When the whole posture is initialized based on the mechanical origin, the center of gravity G of the whole robot is located between two vertical planes containing the two positions. In the initialization, a first joint portion  7 , a second joint portion  8 , and a third joint portion  9  are located between the two vertical planes. Thus, because the whole balance is taken, the origin adjustment is easy.

TECHNICAL FIELD

The present invention relates to a biped locomotion robot.

BACKGROUND ART

A humanoid robot, especially a biped locomotion robot, has beingdeveloped as an autonomous movement machine operable in environmentswhere human beings have to execute difficult activities, such as careactivity and in home and rescue activity in a fire scene. As shown inFIG. 1, such a robot is composed of an element system comprising aplurality of elements (head 101, body 102, and legs 103) which are undersubordinative control of each other based on multiple joints, and anelement relating system which relates the element system (joints 104,105, 106, 107, 108, and 109 as 1-, 2- and 3-axis rotation systems). Thewhole control of the element system and the element relating system isdescribed based on multiple variables belonging to each system andmultiple parameters. However, it is difficult to separate independenceand subordination between the multiple variables with high precision inthe development phase. It is also difficult to describe a foot risingmovement and a foot grounding movement that are associated with walkingcorrectly.

When a theoretical walking movement and an actual walking movement donot coincide with each other, the cause of the discrepancy depends onsome of the variables. Mechanical elements of the plurality of elementshave physical parameters, and the rigidity and mass of each mechanicalelement have an important influence on the walking movement. For thisreason, it is difficult to theoretically analyze whether the instabilityof control depends on the mass of the head or the rigidity of the bodyor leg. Additionally, it is difficult to analyze the discrepancy wheneach mechanical element is not manufactured according to theory.

Therefore, it is important to design a biped locomotion robot such thatthe changeable ranges of the parameters of all the elements arerestricted in consideration of physical characteristics between theelements, for the purpose of facilitating the analysis and confirmingthe quality of the design. It is important to cause effectiveattenuation of influence between composite rotation systems. Thedefinition of reasonable rules about the adjustment and initializationof a mechanical origin defining an initial condition of the movement isimportant to prove the quality of the design.

DISCLOSURE OF INVENTION

An object of the present invention is to provide a self-controlled bipedlocomotion robot with a small size.

Another object of the present invention is to provide a biped locomotionrobot in which movement analysis is easy.

Another object of the present invention is to provide a biped locomotionrobot in which the initialization of composite coordinate systems iseasy.

Another object of the present invention is to provide a biped locomotionrobot in which the control of the whole movement system can be realizedbetter.

In an aspect of the present invention, a biped locomotion robot iscomposed of a fundamental body portion, an upper body housing rigidlycoupled to the fundamental body portion, two leg portions movablycoupled to the fundamental body portion, a foot portion movably coupledto each of the two leg portions, a head portion movably coupled to theupper body housing, and two arm portions movably coupled to the upperbody housing. It is desirable that the fundamental body portionfunctions as a mechanical origin.

The biped locomotion robot may be further composed of two handleportions provided for opposing attachment sections of the fundamentalbody portion. Thus, the workability and custody can be improved.

Also, the center of gravity of the biped locomotion robot is desirablylocated between vertical planes, each of which passes corresponding endsof the attachment sections of the handle portions to the fundamentalbody portion, when the biped locomotion robot is in an initial state.

Also, each of the two leg portions may be composed of a first linkfunctioning to support the fundamental body portion through a firstjoint portion and a second link functioning to support the first linkthrough a second joint portion. In this case, it is preferable that ahorizontal rotation axis of the first joint portion and a horizontalrotation axis of the second joint portion are located between thevertical planes, each of which passes through corresponding ends of theattachment sections of the two handle portions to the fundamental bodyportion, when the biped locomotion robot is in the initial state.Moreover, each of the foot portions may support a corresponding one ofthe second links through a third joint portion. It is preferable that ahorizontal rotation axis of the third joint portion is located betweenvertical planes, each of which passes through the corresponding ends ofthe attachment sections of the two handle portions to the fundamentalbody portion, when the biped locomotion robot is in the initial state.

Also, when each of the two leg portions is composed of a first linkprovided to support the fundamental body portion through a first jointportion, and a second link provided to support the first link through asecond joint portion, it is preferable that the rigidity of the firstlink is lower than that of the fundamental body portion, and therigidity of the second link is lower than that of the first link. It ispreferable that the first joint portion has a vertical rotation axis.

Also, it is desirable that the first joint portion has a verticalrotation axis.

Also, it is desirable that the upper body housing is coupled to thefundamental body portion to provide a gap region between the upper bodyhousing and the fundamental body portion, and an energy source isarranged in the gap region.

Also, the biped locomotion robot may further include a control unitprovided for a back of the upper body housing.

Also, in another aspect of the present invention, a biped locomotionrobot is composed of a fundamental body portion, two first links tosupport the fundamental body portion through a first joint portion, anda second link to support a corresponding one of the first links througha second joint portion. The rigidity of the first link is lower thanthat of the fundamental body portion and the rigidity of the second linkis lower than that of the first link. Also, the biped locomotion robotis further composed of a foot portion to support a corresponding one ofthe second links through a third joint portion. Mechanical stresstransferred instantaneously through a double pendulum system (3, 4, 7,8) between the fundamental body portion and the foot portion is relaxedor damped on the grounding of the foot portion. Thus, the control ofmechanical origin for a control system of the fundamental body portionbecomes easy. As a result, it becomes easy to position the second link.Moreover, the positioning of the foot portion attached to the secondlink with the minimum rigidity becomes easy.

In another aspect of the present invention, the biped locomotion robotis composed of a fundamental body portion in which a mechanical originis set, a first link to support the fundamental body portion through afirst joint portion, a second link to support the first link through asecond joint portion, and a third link to support the second linkthrough a third joint portion. The fundamental body portion has handleportions, and the handle portions are coupled to the fundamental bodyportion at two positions. It is desirable that the center of gravity (G)of the robot is located between two vertical planes passing through thetwo positions in the initialization of the whole posture with respect tothe mechanical origin. As a result, the rotation moment when the wholeof robot is carried is small, so that the stability of the robot is highand the carrying of the robot is easy. In case of the initialization, itis desirable that the rotation axis of the first joint portion, therotation axis of the second joint portion, and the rotation axis of thethird joint portion are located between the two vertical planes.Especially, the two positions corresponding to the two vertical planesare determined as two separate positions in a front direction in case ofthe initialization. It is desirable that the handle portions form areference plane to the mechanical origin in case of the initialization,and the grounding surface of the foot portion can be adjusted based onthe reference surface of the handle portion. Especially, by adjustingthe foot portions such that the reference surface of the handle portionsis parallel to the grounding surfaces of the foot portions, theadjustment of the foot portions to the origin point becomes easy. Thehandle portions may be outside an exterior body such as a body sectioncover and may be exposed. Thus, the regular initialization work becomeseasy.

In another aspect of the present invention, the biped locomotion robotis composed of a fundamental body portion, an upper body housingsupported by the fundamental body portion, first links to respectivelysupport the fundamental body portion through first joint portions,second links to respectively support the first links through secondjoint portions, foot portions to respectively support the second linksthrough third joint portions, and an upper portion supported by theupper body housing through a fourth joint portion. The upper bodyhousing is attached to the fundamental body portion with a highrigidity, and arm portions and a head portion are supported by the upperbody housing through joint portions. In this way, the rigidity of thesupport structure to support the head portion and the arm portions canbe maintained high. The upper body housing is supported by thefundamental body portion through side plate sections to form a gapregion, and an energy source (cell battery and so on) is arranged in thegap region. Thus, the use efficiency of the space is high.

Many various holes and an attachment structure are provided for thefundamental body portion for attachment of the upper portion and thelower portion. Therefore, the fundamental body portion is formed ofthick light alloy as a whole. A proper reinforcement structure may beused for the fundamental body portion.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view showing a conventional biped locomotionrobot;

FIG. 2 is a perspective view showing a portion of a biped locomotionrobot according to an embodiment of the present invention;

FIG. 3 is a side view geometrically showing a leg portion of the robotshown in FIG. 2;

FIG. 4 is a perspective view showing an upper body housing;

FIG. 5 is a perspective view showing an upper body housing with a cover;

FIG. 6 is a side view of the biped locomotion robot shown in FIG. 2;

FIG. 7 is a front view showing a part of the biped locomotion robotshown in FIG. 2;

FIG. 8 is a perspective view showing an arm portion, a body section, anda head portion;

FIG. 9 is a front view showing a method of adjusting a mechanical originin the biped locomotion robot according to the embodiment of the presentinvention;

FIG. 10 is a perspective view geometrically showing a handle portion;

FIG. 11A is a perspective view showing the method of adjusting themechanical origin in the biped locomotion robot according to theembodiment of the present invention, and FIG. 11B is a diagramgeometrically showing the method of adjusting the mechanical origin;

FIG. 12 is a perspective view showing a body portion with the cover, inwhich a power supply section is installed;

FIG. 13 is a perspective view showing the body portion of the bipedlocomotion robot according to the embodiment of the present invention;

FIG. 14 is a perspective view showing the fundamental body portion;

FIG. 15 is a side expanded view showing the leg portion; and

FIG. 16 is a plan view of the fundamental body portion shown in FIG. 14.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a biped locomotion robot of the present invention will bedescribed in detail with reference to the attached drawings.

FIG. 2 is a perspective view of the biped locomotion robot according toan embodiment of the present invention. Referring to FIG. 2, the bipedlocomotion robot of the present invention is composed of a fundamentalbody portion 6, and a body section 1 and two leg portions 2 with respectto the fundamental body portion 6. A control unit 26 is provided on therear side of the body section 1. In FIG. 2, only one leg portion isshown.

Referring to FIG. 3, the fundamental body portion 6 is a highly rigidbody. The fundamental body portion 6 is supported by 2-axis rotatably byeach of the leg portions 2. Each leg portion 2 is supported by 2-axisrotatably by a foot portion 5. Also, the fundamental body portion 6 isprovided with two side plate sections 12 (not shown in FIG. 3) for a gapto stand up in both side ends of the fundamental body portion 6, asshown in FIG. 4.

Each leg portion 2 has a first leg portion 3 or first link 3 and asecond leg portion 4 or second link 4. The first leg portion 3 or firstlink 3 is coupled to the fundamental body portion 6 through a 2-axisrotatable first joint portion 7. The second leg portion 4 or second link4 is coupled to the first leg portion 3 through a 1-axis rotatablesecond joint portion 8. The foot portion 5 is coupled to the second legportion 4 through a 2-axis rotatable third joint portion 9. The footportion 5 partially has a flat foot back surface contacting a flat flooror flat ground. It should be noted that in this example, the leg portion2 and the foot portion 5 are coupled 2-axis rotatably. However, the legportion 2 and the foot portion 5 may be coupled 1-axis rotatably.

In this way, the second leg portion 4 is supported by the foot portion 5through the third joint portion 9, and the first leg portion 3 issupported by the second leg portion 4 through the second joint portion8. Moreover, the fundamental body portion 6 is supported by the firstleg portions 3 through the first joint portions 7.

As shown in FIG. 4, the body section 1 has an upper body housing 11. Theupper body housing 11 is formed of light alloy as a unit. The upper bodyhousing 11 has a proper thickness and is formed to have a high rigidity.The upper body housing 11 is rigidly coupled to the fundamental bodyportion 6 with the side plate sections 12 for the gap and is supportedby the fundamental body portion 6. The upper body housing 11 isseparated from an upper portion of the fundamental body portion 6 in anupper vertical direction by the side plate sections 12. A battery cellcase 17 is detachably provided in the gap region formed between theupper portion of the fundamental body portion 6 and the lower portion ofthe upper body housing 11.

As shown in FIG. 4, the upper body housing 11 has a head attachment hole19 in the upper portion 18. Also, the upper body housing 11 has armattachment holes 23 in the side portions 11.

Two handle portions 13 are provided for attachment portionscorresponding to the side plate sections 12 on both sides of thefundamental body portion 6. In more detail, the two handle portions 13are firmly attached to attachment portions 14 on the both side edges ofthe fundamental body portion 6 to oppose to each other. Each of the twohandle portions 13 is attached to the attachment portion 14 at twopositions P and Q. It is preferable that the two corresponding positionsP and the two corresponding positions Q are located on a same plane.Also, it is desirable that the plane is parallel to a horizontal plane,namely, is orthogonal to a vertical axis. Especially, it is desirablethat the two positions P and Q are located on a reference plane whichpasses a mechanical origin to be described later. As shown in FIG. 3, itis desirable that the center of gravity G of the total mass when thebiped locomotion robot is complete is positioned on a vertical planewhich passes a middle point of the two positions P and a middle point ofthe two positions Q, or in the neighborhood of the vertical plane.

As shown in FIG. 5, the fundamental body portion 6 and the upper bodyhousing 11 are covered by a body section cover 16. FIG. 6 and FIG. 7show the whole biped locomotion robot when the body section cover 16 isattached to the fundamental body portion 6 in this way. In this case,only one leg portion 2 is shown in FIG. 7. The handle portion 13 isexposed outside the body section cover 16. The body section cover 16 hasopenings corresponding to the head attachment hole and arm attachmentholes 24 in the upper body housing 11.

As shown in FIG. 8, the head portion 22 is attached to the upper bodyhousing 11 such that the head portion 22 is adjusted in axis to the headattachment hole 19 of the upper body housing 11 through the body sectioncover 16 and is supported in the vertical direction. Like the headportion 22, the arm portions 25 are adjusted in axis to the armattachment holes 23 and 24 of the upper body housing 11 through the bodysection cover 16, and is attached to the upper body housing 11 2-axisrotatably. That is, as shown in FIG. 8, the arm portion 25 has thedegrees of freedom in multiple axes and is attached to the upper bodyhousing 11 freely in swing and turning. The carrying type control unit26 is arranged on the back side of the body section cover 16 and isattached to the fundamental body portion 6, as shown in FIG. 2.

FIG. 9 shows a method of adjusting a mechanical origin. An elementsystem is composed of a fundamental body portion system S1, first linksystems S2, second link systems S3 and foot systems S4. The state shownin the figure is when a walking examination is carried out with an armsystem omitted. The first link system S2, the second link system S3 andthe foot system S4 are provided for either side but are treated as asingle system.

As shown in FIG. 10, the handle portion 13 has a unitary body oftransverse bar portions 13A extending in transverse directions and abridge portion 13B extending in a front direction. The surface of thebridge portion 13B, especially, the lower surface of the bridge portion13B is formed as the reference surface SS1 for the mechanical origin. Areference surface SS2 corresponding to the reference surface SS1 for themechanical origin on either side is formed as the upper surface of arigid body pillar 31 which stands up from a reference horizontal floorsurface SS3. The coincidence of the reference surface SS1 for themechanical origin and the reference surface SS2 may be detected by atouch sensor (not shown) which detects contact of the rigid body pillar31 and the handle portion 13.

The biped locomotion robot has a weight to the extent for a human being,and is carried by using the handle portions 13 on both sides such thatthe reference surface SS1 for the mechanical origin is made to coincidewith the reference surface SS2 of the two rigid pillars 31. Or, thebiped locomotion robot is operated by a remote radio control such thatthe reference surface SS1 for the mechanical origin is made to coincidewith the reference surface SS2 of the two rigid pillars. After that, thethree coordinate systems S2, S3, and S4 are initialized using thecoordinate system S1 as reference. That is, in the initial state, theelement system is reset to the origins of all the coordinate systems S1,S2, S3, S4.

FIGS. 11A and 11B show an allowable range of the mechanical origin. Thespace formed between a vertical plane 32 containing both points P and Pof the handle portions 13 on both sides and a vertical plane 33containing both points Q and Q of the handle portions 13 on both sidesis defined as the allowable range. The control target is that thehorizontal rotation axis 10 extending in a horizontal direction in thefirst joint portion 7, the horizontal rotation axis 8H extending in ahorizontal direction in the second joint portion 8, and the horizontalrotation axis 9H extending in a horizontal direction in the third jointportion are located between the two vertical planes 32 and 33. It is notnecessary that the horizontal rotation axes 7H, 8H and 9H are located ona single vertical plane. Rather, it leads excellent stability that thehorizontal rotation axes 7H, 8H and 9H are not located on the singlevertical plane. The whole mass distribution in the robot is designedsuch that the center of gravity G of the whole biped locomotion robot isin the allowable range when the horizontal rotation axes 7H, 8H and 9Hare in such an allowable range. The grounding surface of the footportion 5 is contained in this allowable range. The rotation position ofa servomotor or rotation drive section corresponding to each jointportion is rest and initialized when the adjustment of the center ofgravity is ended.

It should be noted that in this example, the handle portions 13 areattached to the side portions 14 of the fundamental body portion 6.However, the handle portions 13 may be provided as protrusion sections(not shown). Also, it is not necessary that the handle portions 13 areon a same horizontal plane. If the position of the center of gravity islocated on a slant plane passing through the handle portions 13, it ispossible to stabilize the posture of the robot easily. The adjustment ofthe origin by the robot itself is possible by using the handle portionsand the reference surface.

Various parameters are contained in the walking control. It has beenproved that impact relaxation, proper rigidity and the optimization ofmass of a movement body are important physical factors for the walkingcontrol. In the biped locomotion robot of the present invention, thefollowing relations are set.

-   (1) The rigidity of the fundamental body portion 6 or the rigidity    of the fundamental body portion 6 and the object rigidly coupled to    the fundamental body portion 6>the rigidity of the first leg portion    3>the rigidity of the second leg portion 4,-   (2) The total mass of all the objects weighting on the fundamental    body portion 6>the mass of the first leg portion 3>the mass of the    second leg portion 4, and-   (3) The condition (1)+the condition (2)

The rigidities may be defined based on the flexural rigidity or thetorsional rigidity when the both ends of each object are supported and aload or pressure is applied to a predetermined position or region. It isimportant that the rigidity of the object coupled to the fundamentalbody portion 6 and located in a further distance downwardly from thefundamental body portion 6 is lower and smaller in mass. The conditions(1), (2) and/or (3) facilitate the analysis of the variable dependenceand parameter dependence in the directional control. For example, whenthe mass of the foot portion 5 is larger, the movement of the footportion 5 has a large influence on the control of the whole of systems.Thus, it is difficult to determine whether the movement of the whole ofsystems depends on the pursuit of the servomotor or the centrifugalmovement of the foot portion 5 with a large inertia (inertia mass).However, if the mass of the foot portion 5 is set small, it can bedetermined that the movement of the whole of systems depends on thepursuit of the servomotor largely. This depends strongly on the rigidityof each system especially. The first and second links are properly givenwith high rigidities and the rigidities of them are designed to be lowerthan the rigidity of the fundamental body portion.

When the attachment portions of the handle portion are determined forthe gravity center to be located in the neighborhood of a horizontalregion containing the handle portions 13, the stability is good when thewhole robot is carried by using the handle portions 13. Especially, whenthe robot is installed on the stiff pillar by using the handle portions13, it is easy to adjust the positions of the foot portions 5 to thehandle portions 13 such that the grounding surfaces of the foot portions5 are parallel to the reference plane of the handle portions 13.

In case that the arm portions 25 and the head portion 22 are attachedfreely in swinging to the fundamental body portion 6 with the highestrigidity or the upper body housing 11 having of a high rigidity andcoupled to the fundamental body portion 6 in the robot, the light weightof the whole system can be realized. The cell battery is insertedbetween the fundamental body portion 6 and the upper body housing 11 anduse efficiency of the space can be improved while keeping the rigidity.

FIG. 12 shows the body section cover 16 and the carrying type controlunit 26. FIG. 13 shows a part of the fundamental body portion 6 when anupper portion 26A of the carrying type control unit 26 is removed and apart of the body section cover 16 is opened. FIG. 14 is a perspectiveview of the whole of fundamental body portion 6. In FIG. 14, the arrow Fshows the front direction. The fundamental body portion 6 is formed oflight alloy casting as a unit to have a high rigidity and a properthickness in the vertical direction. Two positioning holes 41corresponding to the two leg portions are formed in the fundamental bodyportion 6. To position each leg portion, a positioning pin hole 45 isformed. The two leg portions are firmly coupled to the fundamental bodyportion 6 with bolts passing through bolt holes 44 which are formed inthe fundamental body portion 6. A reinforcement rib 49 is formed in across in each of the two positioning holes 41.

FIGS. 15 and 16 show a structural section 52 of the first joint portion7. The structural section 52 of the first joint portion 7 has a fixationsection 52A and a rotation section 52B. The top section of the fixationsection 52 a of the structural section 52 is formed to have an outercircular cylinder surface 54. The circular cylinder surface 54 is fit tothe positioning hole 41 shown in FIG. 14 coaxially. In case of theattachment of the first joint portion 7, the positioning pin 55 whichstands upwardly from a surface of the fixation section 52 a is insertedin the positioning pin hole 45 of FIG. 14 to determine the positionrelation of the structural section 52 and the fundamental body portion6. The structural section 52 and the fundamental body portion 6 iscoupled firmly in a high rigidity with bolts (not shown) passing throughbolt hole 56 on the side of the structural section 52 and the bolt holes44 on the side of the fundamental body portion 6.

The foot portion 5 is provided apart from the center of gravity G and iscontrolled to have the degrees of freedom of multiple axes through thefirst leg portion 3 and the second leg portion 4. Therefore, themovement control of the foot portion 5 in case of the foot risingmovement and the foot grounding movement is more faithfully carried outwith respect to the reference coordinate system which is fixed on thefundamental body portion 6, comparing a case that the first leg portion3 and the second leg portion 4 have higher rigidities than thefundamental body portion 6. Thus, the first joint portion 7 is rotatablewith respect to the fundamental body portion 6 in one axis or two axes.

In the biped locomotion robot of the present invention, the originadjustment can be carried out easily in a high precision. Especially,the rigidity is lower in a portion further distant from the mechanicalorigin. Therefore, the grounding impact can be attenuated easily at theportion further distant from the mechanical origin. The control of therotation moment in the floating state of the foot portion becomes easybecause of the lower rigidity and the fact that the portion furtherdistant from the mechanical origin has a smaller mass. As a result, theinitialization of the control on the grounding of the foot portionbecomes easy. The handle portions are provided on positions near thecenter of gravity so that the stability is good. When the bipedlocomotion robot is in the stationary condition by fixing the mechanicalorigin using the handle portions, the initialization of the system ofthe robot is carried out. Therefore, the initialization work is simple.

1. A biped locomotion robot comprising: a fundamental body portion; twoleg portions, each of which comprises: a first link provided to supportsaid fundamental body portion through a first joint portion, and asecond link provided to support said first link through a second jointportion; and a foot portion movably coupled to each of said two legportions through a third joint portion, wherein a rigidity of said firstlink is lower than that of said fundamental body portion, and a rigidityof said second link is lower than that of said first link, wherein arigidity, of said first link is lower than that of said fundamental bodyportion, and a rigidity of said second link is lower than that of saidfirst link, wherein the rigidity of said first link is determinedbetween a top end and a bottom end of the first link, and the rigidityof said second link is determined between a top end and a bottom end ofthe second link and the rigidity of the fundamental body portion isdetermined between a top end and a bottom end of the fundamental bodyportion.
 2. The biped locomotion robot according to claim 1, whereinsaid fundamental body portion further comprises two handle portionsprovided in portions of said fundamental body portion which oppose eachother.
 3. The biped locomotion robot according to claim 2, wherein saidtwo handle portions are provided in an initial state such that a gravityof said biped locomotion robot is located in a region defined byvertical lines passing through ends of an attachment portion of each ofsaid two handle portions.
 4. The biped locomotion robot according toclaim 2, wherein said two handle portions are provided in an initialstate such that a horizontal rotation axis of each of said first tothird joint portions is located in a region defined by vertical linespassing through ends of an attachment portion of each of said two handleportions.